title: Exploring carbohydrate-peptide interactions in the gas phase: structure and selectivity in complexes of pyranosides with N-acetylphenylalanine methylamide.
abstract: The physical basis of carbohydrate-peptide interactions has been explored by probing the structures of a series of complexes generated in a solvent-free environment under molecular beam conditions. A combination of double-resonance IR-UV spectroscopy and quantum-chemical calculations has established the structures of complexes of the model, N-acetyl-L-phenylalanine methylamide, bound to the α and β anomers of methyl D-gluco- and D-galactopyranoside as guests. In all cases, the carbohydrates are bound through hydrogen bonding to the dipeptide chain, although with some differing patterns. The amino acid host "engages" with the most suitable pair of neighboring conjugate sites on each carbohydrate; the specific choice depends on the conformation of the peptide backbone and the configuration and conformation of the carbohydrate ligand. None of the structures is supported by "stacking" interactions with the aromatic ring, despite their common occurrence in bound carbohydrate-protein structures.
authors.affiliation: Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK.
authors.forename: Emilio J
authors.initials: EJ
authors.lastname: Cocinero
authors.forename: Pierre
authors.initials: P
authors.lastname: Çarçabal
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Vaden
authors.forename: Benjamin G
authors.initials: BG
authors.lastname: Davis
authors.forename: John P
authors.initials: JP
authors.lastname: Simons
mesh_terms: D005690:Galactose / Q000031:analogs & derivatives / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D005740:Gases; D010649:Phenylalanine; C044228:N-acetylphenylalanine; D005690:Galactose